Between now and the start of fall camps on Aug. 8, meet the players stepping into key roles for the Ducks and Beavers

Who: Karrington ArmstrongPosition: Center Year: Sophomore Height, weight: 6-2, 260 Replaces: Jordan Holmes (first-team all-Pac-10) Lowdown: Three starters along the offensive line, Holmes, Bo Thran and C.E. Kaiser, left the program following their senior seasons. But just one position, center, will likely see a virtual rookie fill the role. Armstrong will enter camp atop the depth chart at center having made just one career appearance, against Portland State. He will compete with redshirt freshmen Hroniss Grasu and Hamani Stevens. The line's other projected starters, seniors Mark Asper, Darion Weems and Ramsen Golphashin, and junior Carson York have appeared in a combined 103 games, easily making Armstrong the least experienced player among the prospective starters. His task is to replace Holmes, an all-conference player, and do so in the heart of the offensive line. Armstrong was an all-state selection at guard out of McQueen High School in Reno, Nev., where he also played defensive line.